Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description must carry the behavioral load. It usefully discloses the dataset contents and the x402 price of $0.002 per call, but it does not describe read-only status, auth/payment flow beyond price, rate limits, or response behavior.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is three tight sentences: dataset scope, usage modes, then pricing. It is front-loaded and every sentence adds concrete information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a three-parameter read tool with no output schema, the description gives enough context: the available fields, the lookup modes, and the payment price. It could be more explicit about combining empty country/region values, but the schema covers those details.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents country, region, and limit. The description only adds that country lookup versus regional listing is possible, without adding syntax or constraints beyond the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific resource (reference database of all 250 countries and territories) and a specific action (look up a single country or list by region). It also enumerates the data fields available, so an agent can tell this apart from unrelated calculator, converter, and lookup siblings.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly states the two primary modes: look up one country or list by region. It does not name alternatives or explicit exclusions, but for this tool the usage context is sufficiently clear from the description and schema.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.